Journal of Research of the National Bureau of Standards Va!. 48, No.1, January 1952 Research Paper 2285 Binding Energies for Electrons of Different Types Charlotte E. Moore and Henry Norris Russell 1 The binding energy of an electron of given type in any state of a neutral or ionized atom ~a.~ b~ defi,ned as that required to remove it along successive terms of a spectral series to Its I1l11It. 'I he data regardll1g electron configurations and limits collected in Atomic Energy Leve!s, Vo lumes I and II! permit th~ calculation of these in a great number of cases. rhe present tables give the maxImum energy res ulting from the addition of an electron of given type (s uch as 4p) to the ground states of singly or doubly ionized atoms of the elements H through Nb; and, when deS irable, to one other low state (two in the cases of Sc and Y). These increase smoothly with atomic number except for a remarkable break after a shell of ten d-electrons has been half filled. 1. Introduction 3. Binding Energy in Complex Spectra The first extensive table of the binding energy In the .more, coml?lex spectra a given electron with which an electron of a given type is attached configuratIOn gIves rIse to a number of different f to a neutral or ionized atom in a specified energy terms, most ?~ which have three or more components; level was given by one of us 22 years ago [1].2 It is and the addItIOn of a p or d electron to one of these striking evidence of the extraordinarily rapid advance terms u ually produces, in the spectrum of next of spectroscopic theory and analysis during the 5 lower ionization, two triads or pentads of terms of preceding years that more than 80 percent of the different multiplicity. To reduce the tables to data now available for the same spectra were then reas~Hlable bulk, on}y t l~ e lowest term belonging to included, and that very little change would be , ~ !pve~ c~nfi~uratlOn III the spectrum of higher req~~red even in the descri~tive text . A thorough IOmzatI?n IS mcluded; .aJ?d the tabulated binding reVISIOn of the data made III connectIOn with the energy IS taken as the dIfference between the lowest compilation of Bureau Circular 467, Atomic Energy component of this limit and the lowest component Levels [2], has led as a byproduct to the tables given (r~gard l ess of the multiplicity) of any member of below. tnads or pentads of terms arising from it. It thus represents the maximum value for an electron of 2 . Definition a nd Types of Binding Energy the given type. The designation of each term that is included in the tables is given as it appear in This binding energy may be defined as that 1'0- Volume 101' II of Circular 467 [2]. quir,ecl to remove the electron under consideration from the atom in the specified state without changing any quantized relations except the total quantum 4 . Cases With Two Different Limits number of this electron- thus passing to the limit of the spectral series to which the given energy level In . certain important pectra, however, two or belongs. occasIOnally tlnee, electron configuration give terms In the simplest spectra all the series have the at nearly the same level, as in the classical example of the group Ca Il to Cu II where the lowest confi O'u­ same limit. The energy level L' (in cm- I ) correspond­ ing to this limit is given in Circular 467 at the end ration comes sometimes from 3dn- 1 and in other cab e of the table containing the levels [' for the individual from 3dn - 2 48. In uch case the lowest term arising from each of these configurations is adopted as a states. The binding energy (in cm-I ) is L'- [' . In electron-volts it is 0.00012395 (L'- l' ) [3]. tabular limit, and the binding energies from Ca I to In the case of a spectroscopic term with several Cu 1 corresponding to the addition of an electron of components the smallest value of [' should be taken gi ven type to each of them are given in table 1. thus giving the maximum binding energy. ' Those with limit 3dn- 1 are di tinguished by "A" at In spectra in which terms of two multiplicities the head of the column, and the others by "B." arise from the same "running" electron and have the Only terms of group A appear in K I and of type B same limit, the smallest value of [' tabulated for in Zn I. A similar situation, involving 4d and 58 either of the two should be adopted for I', for the electrons appears from Rb I to Cd I. A da h in the same reason. table indicates that no such term exists. Thus in Mg I [4] the lowest value of [' for a 3p For doubly ionized atom a similar situation electron i 21850 for 3p 3 p~, that for 3d is 46403 rarely arises. From Ca HI to Cu III, for example, the lowest level always comes from 3dn - 2. The ad­ for 3d ID 2, while the limit 38 28014 in Mg II is 61669. II The binding energy is therefore '39819 cm- I , or 4.94 dition of 3d or 48 to this level gives the terms in Ca volts, for 3p, and 15266 cm-I or l.89 volts for 3d, as to Cu II thus designated in table 2, which serve as gi ven in table 1. the limits for groups A and B from Ca I to Cu I. The further addition of 48 or 3d, respectively 1 Princeton University Observatory, Princeton, N. J. , Figures in brackets indicate the literature references at the end of this paper. gives the same term in each arc spectrum- namely: 61 ) TABLE 1.- 1\II aximum binding energy oj an electron- neutral atoms ~ctron 18 28 2p 38 3p 3d 48 SPcct~ HI Is 280l> 13.59 28 '80l> 3. 40 2p 'POl> 3.40 38 ' 80l> 1. 51 3p ' P Ol> 1. 51 3d 'D'l> 1. 51 48 'So» O. 85 Hel Is' 180 24. 58 28 ' 81 4. 77 2p ' Pi 3.62 3s ' 8 1 1.87 3p ' Pi 1. 58 3d'D 1. 51 48 '81 0.99 Li I 2s '80l> 5. 39 2p ' P ol> 3.54 3s '80l> 2.02 3p ' P' 1. 56 3d ' D l l> 1. 51 48 '80l> 1. 05 28'180 9. 32 2p ' P o 6.60 38 '81 2.86 3p'P' 2. 03 3d'D 1. 63 48 ' 81 1. 32 Br 2p ' P ol> 8.30 38 '80l> 3.33 3d'D 1. 51 48 ' 80» 1. 48 Cr 2p2 3PO 11. 26 38 ' P o 3. 79 3p IPI 2.73 3d In; 1. 64 48 ' P o 1.58 Nr 2p' 'SIl> 14 . 54 38 'POl> 4. 22 3p '80l> 2.95 3d ' P ll> 1. 58 48 'POl> 1. 70 Or 2p' ' p , 13. 61 3s ' 8; 4. 47 3p ' PI 2.88 3d ' D , 1. 54 48 '8i 1. 78 F 1* 2p' 'Pil> 17. 42 38 • P 'l> 4. 72 3p ' P;l> 3.05 3d'D'l> 1. 54 48 ' P 'l> 1. 85 NCI 2p6 180 21. 56 3s [1 )1H 4.94 3p [0 )1]1 3. 18 3d [0)1]0 1. 54 48 (1)1]2 1. 90 Nal 38 '80l> 5. 14 3p ' P ol> 3. 04 3d ' D 'l> 1. 52 48 ' 80» 1. 95 M g r 38' 180 7. 64 3p'Po 4. 94 3d ID , 1.89 2. 54 AI r 3p ' P ol> 5. 98 48 ' Sol> 2. 84 Si .* 3p" P o 8. 15 48 'Po 3.23 PI 3p' '8il> [10. 55] 3d ' F 'l> 1. 83 48 ' Po» 3. 62 81 3p' 'p, 10. 36 3d ' m 1. 94 48 '8i 3. .83 ('I I 4S ' P 'l> 4. 09 A r 3p61 80 15.76 3d [0)1]0 1. 91 48 [1 Y211 4.21 B A B K ,* 48 2S0}i 4.34 en 1* 3d ' 0 1 3.59 48 ' D I 5.28 4s' 180 6. 11 8c e 'Fll> 2. 97 a 'FI » 5.73 a ' OIl> 6.56 Ti I a ' D o 3.38 6.13 6.83 v a 6S,» 4. 23 a 6D Ol> 6. 80 a 6D ol> 6. 48 a ' F I » 7. 06 Cr J* 2. 38 a 'S, 8.25 a 783 6.76 a ' D o 7. 29 Mn 1* a '8,,, 7.43 Fe I C 3F4 4. 05 7. 90 Co I a 'F,» 8.28 Ni I a 180 5.81 8.67 Cu I 48 'Sol> 10. 44 4s 'Sol> 7.72 4s '0,,, 9. 05 Zn I 4s' 180 9.39 Ga I Ge I A s I 8e I Br 1* ler I Rb t' I Sr 1* ----- - --- - -- --- - - -- - -- ---- -- --- -- --- ---- - --- ---- ----- -- -- ------ - -- -------- ------- - - - -- --- -- --- --- - ----- ---- -- -- --- - -- ---- - - - -- -- -- -- --- -- - - - ---- ---- Y I Zr I Nbr 'An asterisk refers to the special notes on indi vidual spectra. 62 ¥ ..... l T A BLE l.- Maximum binding energ y of an electron- neutral atoms- Continued 4p 4d 58 5p 5d 4p ' P oH 0.85 4d ' D IH O. 85 58 '80l> 0.54 5p ' P oH 0. 54 5d 2D Il> 0. 54 4p , p o 0.88 4d ' D 0.85 58 '81 0.